Gun with removable liner



' Aug. 12, 1930. M. wELLs ET AL 1,772,505

Filed Dec. 1'7, 1928 gwuentou Bordon M.WE1I15 [leu ljs MM EETIT'L Patented Aug. 12, 1930 "1111mm STTES GORDON M. WELLS, or SANDIEGQUALIFORNIA, AND GEORGE McoANNQoF NEW 1 V oAsTLnrELAw- RE, I a

. GUN WITH REMOVABLE LINER Application filed December 1?, 192a. (swam 326,687.?

, (GRANTEn UNDER rim ACT or MARCH a, less as AMENDEDLAIPRIL 30, 1,928; 370 o; G. 75

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

' The subject of this invention is a gun with 5 removable liner.

i In thevmostsucce'ssful type of gun with removable liner, an initial clearance or play space exists between the liner and the surrounding tube but its amount is "very small. The liner is thin and When subjected to pressure on firing it dilates into contact with the tube and then both elements expand together. The tube confines the liner within its elastic limit and by preventing deformation, insures the reestablishment ofthe initial clearance. In those guns which were actually constructed in accordance with the formula, including the principle of initial clearance 20 that the dimensions of the liner andtube be exactly followed. An adherence to such precise requirements would not only preclude quantity production but due to the effect of repeated firing on the tube, it would require that a new linerto replace the worn one which is removed be calibrated to conform 'to the worn tube. This condition defeats the very purpose for which the loose liner is designed.

"In seeking a method whereby all liners may beinterchangeable with respect to all tubes ofa given caliber we have discovered when using a very thin liner, it was essential is illustrated in having a thickness calculated to include a vsafety factor to make it self-sustaining, there is a'recoveryto normal internal dimensions after firing. Considerlng such a barrel as a liner,the outer tube could be ofnegligiblev strengthin so far as restraint of theliner against radial expansion is concerned but, inasmuch as the outer tube must serveto oppose or resist the longitudinalstrains' transmitted to itby the liner during firing, it' would benecessarv to impart to the tube an appreciable strength. The unbalanced relation resulting from a proposition of this character would increase the weight of the gun and nullify the attendant advantages .of

the composite barrel and the removable liner. The relation between "wall thickness and play space must be such that'the liner will; preserve the play space and not be permanently deformed when the play space is at its maximum value due to the tolerances employed. i 1 v *A further advantage resulting from the increasein the thickness of the liner and conducive to interchangeability is the fact that the muzzle portion of the liner can be made self-sustaining and need not be keyed to the tube to prevent its rotation. The omission of the keys at the muzzle'is permitted because of-the'favorable position of other keys in front of the powder-chamber and in line with the projectile.

view, the invention resides in the novel arrangement and combination of parts and in the details of construction hereinafter described'and claimed,it being understood that changes in the precise embodiment of the HIVQIltlOIl herein disclosed may be made Withv in the scope of what is claimed without departing from the spirit of the invention- A practical embodiment'of the invention the accompanying drawings,

wherein:

Fig. l is'a longitudinal sectionalview of WVith the foregoing and other objects in The, gun embodying the principles of the invention comprises a tube Within which 1s a liner 6 made of steel havlng a hlgh elastic limit, this qualitybeing incident to the particular composition of the steel or produced through methods of working or both. In order that theoriginal inner d imensions of the tube may be preserved, irrespective of the extent of lts use, the inner layer of the tube should also be overstramed by working to give it a permanent set or deformation to insure uniformity and the absence of defects.

Having determined composite gun must possess, the correspondtotal wall thickness is approximately equally divided between the liner and the tube as. sucha balanced relation will permit the employment of ample tolerances, favorably distribute the work which the liner and tube must jointly perform and enable the muzzle portion to be self-sustaining. The breech portion of the liner in which the powder. chamber 7 is formed does not bear such a relation in regard'to thickness and thisvariationis made as a manufacturing expedient to facilitate the cold Working; of a liner With a uniformly tapered exterior and a tube with a uniforn'ily tapered interior. c 7

WVith the wall thickness thus selected, the tolerances on the external diameter of the liner and the internaldiameter of the tube which may be safely employed may result in the provision of a play space whichis more than. three times the value of that allowance for play space which was introduced into the gun formula when determining the required strength for the thin liners of prior designs. For example, the value for play space is customarily ,002 inch, whereas, in the gun enibodiying the principles of this invention, the value is ,007 inch. Taking .003 inch as a minimum play space at the breech end, a plus tolerance and a. minus tolerance of .002 inch may respectively be assigned to the internal diameter of the tube and the external diameter of the liner. I V c 7 From a point directly forward of the loca tion of the rotatingband of a projectile, loaded in the gun, the value forplay space increases gradually towards themuzzle where it may be- .007 as a minimum with tolerances allowed. as prescribed. above,

The gradualincrease in the value of the play space from breech to muzzle is inversely proportibnali to; the powder pressureeffective between these points. The additional play the strength which the space at the muzzle is permitted because the strength of the muzzle is such as to make it self-sustaining.

From the foregoing it is to be noted that the smaller value for play space pertains only to a relatively short distance at the breech which distance constitutes only about onesixth of the total length of the liner. Accordingly, the insertion and removal of the liner from the tube may readily be accomplished.

The liner is formed externally with keys 8 a position corresponding to. that occupied the base portion of a projectile 9 in the V bore and these keys are receivable in key-ways 10 formed internally in the tube and disposed in a vertical plane so that the insertion of the linerwill be facilitated. By virtue of the fact that the keys, arein line with that portion of the projectile which on taking the rifling initially imparts torsional strains to the liner, it has been found that the keys usually placed atthe'muzz-le may beomitted. This omission is a matter of great importance inasmuch as the incorporation of muzzle keys has. been attended with considerable difiiculty when provision is made for the independent longi tudinal expansion and contraction of the liner.

Ne claim: a

1. A gun comprising an outer tube, an innor tube, the outer diameter of saidinner tube being less than the inner diameter of said, outer tube to establish at all points therebetween a play space restorable after firing and the Wall thickness of they tubes determined to permit manufacturing tolerances in diameters substantiallydoubling the ,minimum play space.

2. A gun comprising an outer tube, an inner tube,.the outer diameter of said inner tube being less than the inner diameter of said outer tube to establish a play space restorable aft-er firing, said play space having a gradually increasing value in the direction. of the muzzle;

v 3. A gun comprising an outer tube, an inner tube of substantially thesame wall thickness as the outer tube and the outer diameter of the inner tube being less than the inner diameter of the outer tube to. establish at all points therebetween. a play space restorable after firing.

4;. A gun comprising an outer tube, an. inner tube, the outer diameter of the inner tube being less than the inner diameter of the outer tube to establish at all points therebetween a play space restorable after firing and the muzzle portion. of the inner tube being self-sustaining,

5. A gun comprising an outer tube, an inner tube, the outer diameter of the inner tube being less than the inner diameter of. the outer tube to-establish a play space restorable after firing and means preserving the play space located solely at the projectile occupying position of the liner for keying the liner to the tube, said keying means disposed in a vertical plane through the gun.

6. A gun comprising an outer tube, an inner tube, the outer diameter of the inner tube being less than the inner diameter of the outer tube to establish a play space restorable after firing and means preserving the play space located solely at the projectileoccupying position of the liner for keying the liner to the tube.

GORDON M. WELLS, GEORGE M. MGCANN. 

